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Old 05-14-2022, 11:21 PM
nastala nastala is offline
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Join Date: May 2020
Posts: 69
Quote:
Originally Posted by ConnClark View Post
People have run it up at 17psi after disabling the overboost protection valve. The real issue is the stock compressor wheel acts more like a heater above 13psi and it just isn't efficient. This does increase the chance of the compressor wheel grenading.

10 to 12psi is the sweet spot for the stock turbo. I know people who have run a non stock turbo and intercooled up to 22psi with extra fuel. However that is a deep rabbit hole to dive into.

With the wastegate disabled, I ran 25psi for a while. Plotting myself on the compressor map, I am quite confident that I was not overspeeding and was just near the top of the map at a pressure ratio of 2.7 and I think mass flow of 20-25lbs/min at ~4000rpm, inside the max compressor RPM limit of ~155krpm. This was quite inefficient and made the engine lose a lot of top end power through the restrictive turbine housing. 12-15psi really does seem to be the sweet spot with a turned up stock pump.



After removing the turbo and looking in the flange, it is evident why it was so restrictive - the turbine housing inlet is very small and the T3 flange is roughly half wastegate and half turbine by area. I will also be rebuilding this turbo and examining the compressor for any sign of orangepeeling or other damages, and might be able to get it under a metallurgy microscope.
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